Electric valve circuits



ZZZZJGU Nova 26, 194i). B. D. BEDFORD ELECTRIC VALVE CIRCUITS Filed Sept. 22, 1937 3 Sheets-Sheet l TIME- HI 8 O 1 m m a e P: v D Tl w w ,0 w 8 m w v w ,w 5 4 4 3 3 AI 6 7 8 9 2 MW 5 4 4 A, w 3 9 4 0 4/ Z 3 3 4 5 6 r 5 3 A A 5 5 4 2 3 5 w 6 n F I 4 .I 5,, 5 z 5 5 B 5 I 5 9 7L 4 3 v 2 m 9 9 J B 7 m m 8 m 8 d P W "m n d P e o B WL 0 w m H g y b BEDFQRD ELECTRIC VALVE CIRCUITS Filed Sept. 22, 1937 3 Sheets-Sheet 2 Inventor: Burn ice D. Bedforci H is; Attorney NW0 T1949 m. BEDFORD ELECTRIC VALVE CIRCUITS I Filad Sept. 22, 1937 3 Sheets-Sheet 3 Patented Nov. 26, 1940 PATENT OFFICE ELECTRIC VALVE CIRCUITS Burnice D. Bedford, Schenectady,

N. Y., assignor to General Electric Company, a corporation of New York Application September 22, 1937, Serial No. 155,142

29 Claims.

My invention relates to electric translating apparatus and more particularly to electric Valve circuits.

In electric valve translating apparatus it is frequently desirable to provide arrangements for controlling the power factor at which energy is transmitted to or received from associated alterhating current circuits. Furthermore, in the control of electric valve translating apparatus, particularly in the control of electric valve inverters, for transmitting energy from direct current circuits to alternating current circuits, and in frequency changing apparatus for transmitting energy between alternating current circuits of the same or different frequencies, it has been found desirable to maintain predetermined minimum commutating angles and voltages of the electric valve means in order to maintain the desired precision and reliability of operation of the electric valve translating apparatus. This problem is of considerable importance in connection with the control of electric valve means of the type employing ionizable mediums, such as gases or vapors, where the control members or grids are generally ineffective to render the electric valve means nonconductive after an electrical discharge has been established and where it is necessary to impress on the anode a potential which is negative relative to that of the cathode to render the electric valve means nonconductive. By commutating voltage I refer to that negative voltage which is impressed across the anode and cathode of an electric valve means for a time equal to or greater than the time of deionization of the medium to render the electric valve means nonconductive. Of course, it is to be understood that this commutating voltage may be derived from various associated apparatus. One of the principal ways is the so-called phase or anode 40 commutation in which the various voltages of a polyphase system are employed to render the electric valve means nonconductive at the predetermined desired instants effected by rendering conductive other electric valve means in the system.

It is an object of my invention to provide a new and improved electric valve translating apparatus.

It is another object of my invention to provide a new and improved control system for electric valve apparatus to control the power factor at which energy is transmitted to or received from associated alternating current circuits.

It is a further object of my invention to provide a new and improved control system for electric valve apparatus whereby the commutating angle and voltage are controlled or maintained at predetermined values.

In accordance with the illustrated embodiments of my invention, I provide a new and improved electric valve translating system for controlling the power factor at which energy or power is interchanged between alternating current circuits and direct current circuits, or between alternating current circuits of the same or different frequencies. More particularly, I provide control circuits which are responsive to the commutating voltage, or, in other words, to the negative anodecathode voltages of the electric valve apparatus to control the translating system, thereby controlling the power factor. In several embodiments of my invention discussed hereinafter the negative anode-cathode voltage, or the commutating voltage, of an electric valve means is utilized to control the phase of a periodic voltage impressed on a control member of the electric valve means to accomplish the desired regulation or control of the commutating voltage, commutating angle and power factor of the translating apparatus. In another embodiment of my invention, inductive devices are associated with the translating apparatus to control the power factor at which energy is transmitted between the associated circuits and the inductive devices are controlled in accordance with the commutating voltages of the electric valve means.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. Fig. 1 of the accompanying drawings diagrammatically illustrates a simplified embodiment of my invention as applied to an arrangement for controlling an excitation circuit for electric valve means to maintain a predetermined commutating angle and voltage; Fig. 1a represents certain operating characteristics of the arrangement shown in Fig. 1; Figs. 2, and 3 diagrammatically illustrate modifications of the arrangement shown in Fig. 1 as applied to electric valve translating apparatus for transmitting power to or receiving power from a polyphase alternating current circuit. Fig. 4 diagrammatically illustrates another embodiment of my invention which includes means responsive to the anode-cathode current of an electric valve means and a polyphase electric valve translating system for controlling the phase of the control voltage to control the commutating voltage, commutating angle and power factor, and Fig. 5 diagrammatically shows an embodiment of my invention utilizing inductive devices for controlling the translating apparatus to control the power factor, commutating voltage and commutating angle in accordance with the commutating voltage of the electric valve apparatus.

Referring now to Fig. 1 of the accompanying drawings, I have diagrammatically illustrated a simplified embodiment of my invention as applied to an electric valve means I connected in an electric circuit 2 which is controlled by the electric valve means I. The electric valve means I is preferably of the type employing an ionizable medium, such as a gas or a vapor, and includes an anode 3, a cathode 4 and a control member 5 which is effective to render the electric valve I conductive during positive half cycles of applied anode-cathode voltage when a voltage of predetermined value is impressed thereon. While for the purposes of simplifying the description of my invention I have represented the electric valve I as connected in a circuit separate from any associated translating apparatus, it is to be understood that the electric valve means I may be connected in any conventional translating system such as those represented in Figs. 2-5.

I employ an excitation circuit 6 for impressing on control member 5 of electric valve I a. suitable periodic voltage to render the electric valve I conductive during predetermined recurring intervals of time. Excitation circuit 6 may include an inductive device I for generating a voltage of peaked wave form and may comprise a core member 8 having a restricted saturable portion 9, a. primary winding III which is energized from any suitable source of alternating current, such as circuit II, a secondary winding I2 in which there is induced an alternating voltage of peaked wave form and a control winding I3 which controls the magnetization of the core member 8, and hence controls the phase of the alternating voltage of peaked wave form relative to the voltage impressed on primary winding II].

To impress on the control member 5 a negative unidirectional biasing potential, I employ a self-biasing type of circuit comprising a parallel connected impedance element I 4 and a condenser I5. The impedance element I4 may be of the type having a nonlinear impedance-current characteristic. A parallel connected unidirectional conducting device I6 and an impedance element I1 are connected in series relation with the control member 5 and winding I2 of the inductive device 1 in order to provide a relatively low impedance path for the flow of normal control member current and to provide a relatively high impedance to the flow of control member current incident to the deionization of the medium of the electric valve means I. The impedance element I1 is preferably noninductive to permit the flow of normal control member current in the event the unidirectional conductive device I5 becomes defective. This feature is disclosed and claimed in my copending application Serial No. 88,825 filed July 3, 1936, now Patent No. 2,114,828, issued April 19, 1938, and assigned to the assignee of the present application.

In order to control the commutating voltage and angle of the electric valve means I and hence to control the power factor of associating translating apparatus, I provide a control circuit I8 which is responsive to the commutating voltage of electric valve means I, or, in other words, responsive to the negative anode-cathode voltage of the electric valve means I. The control circuit I8 controls the phase of the alternating voltage of peaked wave form impressed on control member 5 of electric valve means I and comprises a suitable unidirectional conducting device or rectifier I9 which is oppositely disposed relative to the electric valve means I. The control circuit I8 also includes a filter circuit which may comprise a capacitance 20 and an inductance 2I which are connected in series relation with the unidirectional conducting device I9. Control winding I3 of saturable inductive device I is energized in accordance with the unidirectional voltage appearing across capacitance 20 and is, therefore, supplied with the unidirectional current which controls the magnetization of the core member 8. A suitable circuit controlling means, such as a voltage divider 22, may be interposed between the circuit I8 and the control winding I3 to adjust or control the current transmitted thereto.

The operation of the embodiment of my invention diagrammatically shown in Fig. 1 will be explained in connection with the operating characteristics represented in Fig. 1a. Curve A represents the anodc-cathode voltage of the electric valve means I when it is connected in a translating circuit where the desired period of conductivity is substantially 120 electrical degrees during each cycle of applied anode-cathode voltage. The alternating voltage of peaked wave form impressed on control member 5 serves to render the electric valve I conductive at the desired instants. The electric valve means conducts current until another electric valve means in the system effects commutation of current therefrom, and this commutation of current is effected by impressing a transient negative voltage on the anode 3. Referring to Fig. 1a, the electric valve means I may be considered as conducting current immediately prior to the time at which time current is commutated from elecitric valve means I to another electric valve means in the translating apparatus (not shown). The voltage as represented by the portion of curve A between lines a and b is termed the commutating voltage of the electric valve I and is the voltage which is effective in commutating current therefrom. At time c the positive impulse of voltage impressed on control member 5 renders the electric valve means conductive and it conducts current during the interval c-d. Since the unidirectional conducting device I9 is oppositely disposed relative to the electric valve I in circuit 2, it is to be understood that during the interval a-b when the anode 3 of electric valve I is negative relative to the cathode 4, the unidirectional conducting device I9 will conduct current through a circuit including the serially connected inductance 2| and the capacitance 20, thereby charging the capacitance 20. Due to the filtering action of this portion of the circuit, the voltage impressed on control winding I3 of the saturable device I will remain unidirectional and this winding will be supplied with a unidirectional control current. By the proper adjustment of the voltage divider 22, I may control or adjust the amount of current transmitted to winding I3.

In electric valve inverter circuits of the constant potential type, an advance in phase of the voltages impressed on the control members of the electric valve means efiects an increase in commutating voltage. The control circuit I8 supplies a variable unidirectional current to the control winding l3 of device I which controls the phase of the alternating voltage impressed on control member 5 to maintain the commutating voltage and commutating angle at predetermined values. Therefore, if the electric valve I is connected in a constant potential inverter system, the control circuit l8 may be arranged to effect an advance in phase of the alternating voltage impressed on control member 5 when the commutating voltage decreases below a predetermined value to reestablish the desired value of commutating voltage, commutating angle, and power factor of the translating apparatus. Conversely, the control circuit will effect a retardation in phase of the alternating voltage impressed on control member 5 to decrease the commutating voltage and angle when the commutating voltage exceeds the predetermined desired value.

Fig. 2 diagrammatically shows another embodiment of my invention as applied to a polyphase translating apparatus for transmitting energy between the three phase alternating current circuit 23 and the direct current circuit 24. The translating apparatus includes a transformer 25 having primary windings 26 and secondary windings 21, and an electric valve aggregate including electric valve means 28-33. The electric valves 28-33 are preferably of the type employing an ionizable medium and each includes an anode 34, a cathode 35 and a control member 36. Excitation circuits 31-42 are associated with electric valves 28-33, respectively, and are similar in construction and arrangement to excitation circuit. 6 of Fig. l and corresponding elements thereof are assigned like reference numerals. The excitation circuits 31-22 may be energized from any suitable source and in the arrangement shown in Fig. 2 are shown as being connected to the alternating current circuit 23 through a suitable phase shifting device such as a rotary phase shifter 43. serially connected pairs of electric valves, such as electric valves 28 and 3|, are controlled by excitation circuits 31 and 40 to be rendered conductive 180 electrical degrees out of phase. Each electric valve of the group 2833 is rendered conductive for 120 electrical degrees during each cycle of applied anode voltage and each electric valve conducts current only during 60 electrical degrees with any one of the oppositely disposed electric valves. In this manner the electric valves 28-33 transmit current between circuits 23 and 23.

As an arrangement for controlling the phase of the alternating periodic voltages impressed on control members 36 of electric valves 23-43 in accordance with the commutating voltages thereof, I employ a plurality of unidirectional conducting devices or rectifiers 4 L 23. The rectifying devices 4449, which are energized in accordance with the negative anode-cathode voltage of the electric valves 28-33 respectively, provide electric quantities, such as currents, for energizing control windings l3 of the saturable inductive devices I to regulate or control the power factor at which energy or power is transmitted to or received from the alternating current circuit 23. In the particular arrangement shown in Fig. 2, control windings I3 of saturable inductive devices 1 in excitation circuits 31-39 are connected in series relation. with each other and are connected to be energized in accordance with the resultant current transmitted by rectifying devices 44-46. A suitable filter circuit 50, including inductances 5|, 52 and 53 and a capacitance 54, are interposed between the rectifying devices 4443 to supply a unidirectional current to control windings I3. A suitable current controlling device, such as an adjustable resistance 55, may be connected in series relation with circuit 50 and the control windings iii. In like manner, control windings l3 of the in ductive devices I in excitation circuits 4342 are energized in series relation in accordance with the resultant current supplied by rectifying devices 4l-49 through a suitable filter circuit 53 including inductances 51, 58, 59 and capacitance 69, and a current controlling resistance 6|.

The general principles of operation of the embodiment of my invention shown in Fig. 2 will be explained when the translating apparatus thereof is operating as an inverter to transmit energy from the direct current circuit 24 to the polyphase alternating current circuit 23. Excitation circuits 31-42 render the electric valves 28-33 conductive in a predetermined order and during recurring intervals of electrical degrees. The alternating voltages impressed on control members 36 by the respective excitation circuits determine the instants at which the electric valves are rendered conductive and the phase relation of these voltages relative to the voltages of the associated phases of the three phase alternating current circuit 23 determines the commutating voltage, commutating angle and power factor at which energy or power is transmitted to the circuit 23.

Let it .be assumed that the rotary phase shifter 43 is adjusted to establish a predetermined power factor and commutating angle and voltage condition, and that the resistances 55 and 6! are adjusted in accordance therewith. Rectifying devices 44-49 acting in conjunction with circuits 5!! and 56 and excitation circuits 31-42. operate to maintain or control the commutating voltage, angle and power factor in accordance with the negative anode-cathode voltage of the electric valve means 2833. If it be assumed that the commutating voltage of the electric valves 28-33 decreases to a value below the predetermined value, the reduction in the unidirectional current supplied to control windings l3 effects an advance in phase of the alternating voltages impressed on control members 33 to reestablish the predetermined value of commutating voltage. Conversely, if the commutating voltage of the electric valves increases, the increase in unidirectional current transmitted to control windings i3 will effect a retardation in phase of the voltages impressed on control members 36 to reestablish the desired commutating voltage and commutating angle conditions. It is to be understood that by controlling the commutating angle and voltage the arrangement also controls the power factor at which energy or power is transmitted to or received from circuit 23.

While the operation of the arrangements of Figs. 1 and 2 has been described in connection with electric valve translating circuits operatin as inverters, it will be understood that my in.- vention in its broadest aspects applies to electric valve translating circuits generally. that is, applies to electric valve rectifying, inverting and. frequency changing systems. For example, my invention may be applied to control the excitation of electric valve means used in rectifying systems by employing the instantaneous difference of voltage between various anodes during the commutating interval or intervals.

In Fig. 3 of the accompanying drawings there is diagrammatically illustrated another embodiment of my invention as applied to an electric valve translating apparatus for transmitting energy between an alternating current circuit 62 and a direct current circuit 63 through a transformer 64 having primary windings 65 and secondary windings 66. A smoothing reactance may be connected in series relation with the direct current circuit 63. The translating apparatus also includes electric valves 61, 68 and 69 which are preferably of the type employing ionizable mediums and each includes an anode 10, a cathode H and a control member 12 which is effective to render the electric valve conductive. Excitation circuits 13, 14 and 15 are similar in construction and arrangement to excitation circuit 6 of Fig. 1 and are associated with electric valves 61-69, respectively, and impress on control members 12 thereof alternating voltages of peaked wave form which render the electric valves conductive in a predetermined order. The elements of excitation circuits 13-15 have been assigned reference numerals corresponding to the elements of the excitation circuit 6 of Fig. l. I have found that under unbalanced load conditions it is desirable to provide a control system which quickly and precisely responds to transient conditions to control the commutating voltages of the electric valve apparatus. I provide suitable arrangement including unidirectional conducting devices 16, 11 and 18 which are energized in accordance with the negative anode-cathode voltages of the electric valves 61-69 and which control excitation circuits 14, 15 and 13 which are associated with electric valves 68, 69 and 61, respectively. In other words, each of the control circuits for the electric valves is controlled in accordance with the commutating voltage of another electric valve of the translating system so that the commutating voltage may be precisely controlled under unbalanced operating conditions. It is to be understood that an electric valve in a system of this nature may be controlled in accordance with the commutating voltage of any other electric valve of the translating ap paratus, but preferably in accordance with the commutating voltage of an electric valve immediately preceding it or succeeding it in the order of phase rotation. Control circuits including capacitances 19 and inductances are connected in series relation with rectifying devices 16-18 across electric valves 61-69, respectively, and establish charges on capacitances 19 which vary in accordance with the negative anode-cathode voltages of these electric valves. Suitable current controlling devices, such as adjustable resistances 8|, are connected in series relation with the control or filter circuits including capacitance 19 and inductances 80 to control the unidirectional current transmitted to the control windings I3.

The operation of the embodiment of my invention shown in Fig. 3 is substantially the same as that explained above in connection with the arrangement of Fig. 2. The electric valves 61-69 are rendered conductive in a predetermined order and the excitation circuits 13-15 are controlled in accordance with the commutating voltage of another one of the electric valves to maintain the commutating angle and commutating voltages at predetermined values and hence to control the power factor at which energy or power is transmitted to or received from circuit 62.

Referring now to Fig. 4, another embodiment of my invention is diagrammatically shown as applied to an electric valve translating system in which the conductivities of the electric valves are controlled in accordance with the current conducted by the electric valves to maintain predetermined values of commutating angle, commutating voltage and power factor. An alternating current circuit 82 is connected to a direct current circuit 83 through translating apparatus comprising a transformer 84 having primary windings 85, secondary windings 86 and electric valves 81, 88 and 89. A current smoothing inductance 90 may be connected in series relation with the direct current circuit 83. The electric valves 81-89 are also preferably of the type employing an ionizable medium and each comprises an anode 90, a cathode 9I and a control member 92. Control members 92 are energized by excitation circuits 93-95 which are associated with electric valves 81-89, respectively. Each of the excitation circuits 93-95 may include a saturable inductive device 96 having a primary winding 91, a secondary winding 98 in which there is induced an alternating voltage of peaked wave form and a control winding 90 which controls the phase of the alternating voltage of peaked wave form relative to the alternating voltage impressed on primary winding 91, and hence controls the phase of the voltage impressed on the control member 92 relative to the anode-cathode voltage of the associated electric valve. Current limiting resistances I00 may be connected in series relation with control members 92 and any suitable means, such as a battery IOI, may be employed to impress unidirectional biasing potentials on control members 92. The excitation circuits 93-95 may be energized from any suitable source of alternating current I02 correlated in phase and frequency relative to the anode-cathode voltage of the electric valves 81-89. A suitable phase shifting device, such as a phase shifter I03, may be interposed between the circuit I02 and the excitation circuits to control or adjust the phase of the alternating voltages impressed on the excitation circuits. Of course, the excitation circuits may be connected to the alternating current circuit 82 if desired.

I provide a plurality of inductive devices I04, I 05 and I06, which may be saturable or nonsaturable, each of which is provided with a winding I01 which is connected in series relation with the associated electric valve, and a winding I08 which produces a voltage which varies in accordance with the cornmutating voltage of the associated electric valve. A unidirectional current is supplied to control windings 99 of devices 96 in excitation circuits 93-95 through a plurality of unidirectional conducting devices or rectifiers I09-I I I, which rectify a portion of the voltage generated in winding I08. This circuit is completed through a current controlling or adjusting resistance H2 and a smoothing inductance H3. A capacitance H4 is connected across the common terminals of rectifying devices I09-I II and the common juncture of windings I 08 and acts in conjunction with inductance II3 as a filter circuit.

By proportioning the inductive devices I04-I 06 to be noneaturable, that is to have linear characteristics, the control current supplied to control windings 99 and hence the voltages impressed on control members 92 will vary in accordance with the maximum commutating voltage of the electric valve means. On the other hand, if the inductive devices I04-I06 are proportioned to be saturable and to have a nonlinear characteristic,

the current supplied to the control windings 99 will control the conductivities of electric valves 8'I--89 in accordance with the final rate of change of the commutating voltage. In translating systems which operate over a wide range of current values, a signal proportional to the latter part of the commutating voltage has been found preferable to a signal which is proportional to the maximum commutating voltage. In inverter circuits, a saturable device will produce a signal responsive to the minimum rate of change of the commutating voltage.

The operation of the embodiment of my invention shown in Fig. 4 will be explained by considering the system when energy is being transmitted from the direct current circuit 83 to the alternating current circuit 82. The electric valves 8I-89 are rendered conductive in a pre-determined order by excitation circuits 93-95, respectively, and the phase of the alternating voltages impressed on control members 92 may be initially adjusted by the rotary phase shifter I03 and by adjustment of the resistance H2 which controls the unidirectional current supplied to winding 99. After the initial adjustment, the circuit will operate to maintain a predetermined commutating angle, commutating voltage and power factor of the system. If inductive devices IM-IIIIS are nonsaturable, the voltage generated by windings I08 and hence the unidirectional current transmitted to windings 99 through rectifying devices III9-I II will vary in accordance with the maximum commutating voltage to control the phase of the alternating voltages impressed on control members 92 to maintain this voltage at a substantially constant value. If, on the other hand, the inductive devices I04-I06 are saturable, the phase of the alternating voltages impressed on control members 92 will vary in accordance with the latter part of the commutating voltage and hence will serve to maintain this portion of the characteristic constant. Of course, the power factor and commutating angle and voltage will be maintained at substantially constant values.

Fig. 5 of the accompanying drawings diagrammatically illustrates a still further embodiment of my invention as applied to an electric valve translating system for transmitting energy between an alternating current circuit H5 and a direct current circuit H6 through electric valves H1 and H8. A commutating capacitance H9 may be connected across the alternating current circuit H5 and a smoothing inductance I20 may be connected in series relation with the direct current circuit H6. Interposed between circuit H5 and electric valves H1 and H8, I connect a transformer I2I having a primary winding I22, a secondary winding I23 having an electrically intermediate connection I24 and having a tertiary winding I25, also provided with an intermediate connection I26. Electric valves H1 and H8 include control members I21 energized from an excitation circuit I28 which includes a transformer I29, a biasing source I39 and current limiting resistances I3 I. Excitation circuit I28 may be energized from any suitable source of alternating current I32 and any desirable phase shifting arrangement may be connected to adjust the phase of the periodic voltages impressed on control members I21.

As an additional arrangement for controlling the power factor at which the system transmits energy to or receives energy from the alternating current circuit H5, I employ an inductive device I33 which may be saturable or nonsaturable and which includes windings I34 connected in series relation across circuit H5 and also includes control windings I35 which control the impedance of windings I34 and hence control the reactive volt-amperes taken from or supplied to the circuit H5.

Since windings I25 of transformer I2I are inductively associated with the other windings of the transformer I2I, the voltage induced therein is proportional to the commutating voltages of electric valves I I1 and I I8. In order to supply unidirectional current to control windings I35, I employ unidirectional conducting devices I35 and I31 which are energized from tertiary windings I25. In order to supply unidirectional current to windings I35 of device I33, these windings are connected to rectifiers I36 and I3! through a noninductive impedance such as a resistance I38. The unidirectional current supplied to windings I35 varies in accordance with the anode-cathode voltage of electric valves III and H8. A capacitance I39 may be connected across windings I35 if desired. The unidirectional current is returned to the electric valve circuit through a suitable noninductive voltage divider I40 which is connected to the neutral connection I24 of winding I23 and to the cathodes of electric valves H1 and H8.

In my Patent 1,938,367 granted December 5, 1933, and assigned to the assignee of the present application, I disclose. the claim an arrangement including means, such as inductive devices, for loading. an electric Valve system to maintain a predetermined characteristic thereof. The embodiment of my invention as disclosed in Fig. 5 of the present application is an improvement of the arrangement disclosed in the above mentioned patent. This application is made to protect the further invention which the applicant believes to be present in the aparatus set forth in the claims hereof over and beyond the claims set forth in the above mentioned patent.

The operation of the arrangement shown in Fig. 5 will be explained when the system is operating as an inverter to transmit energy from the direct current circuit H6 to the alternating current circuit H5. After the initial adjustment of the alternating voltages impressed on control members I 21 by excitation circuit I28 and after the adjustment of the voltage divider I49, the system will operate to maintain a predetermined commutating angle, commutating voltage and power factor. Since the voltages induced in tertiary windings 25 vary in accordance with the commutating voltages of electric valves H1 and H8, the magnitude of the unidirectional current supplied to windings I35 will serve as a signal to control the impedances of windings I34 of the inductive device I35 to control the amount of reactive volt-amperes transmitted to or received from circuit H5. In this manner the system power factor is controlled in accordance with the commutating voltages of the electric valves H1 and H8.

While I have shown and described my invention as applied to a particular system of connections and as embodying various devices diagrammatically shown it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, an alternating current circuit, a second circuit, electric translating apparatus for transmitting energy therebetween and including an electric valve means, and means for controlling the power factor at which power is transmitted. to or received from said alternatin current circuit comprising means responsive to the negative anode-cathode voltage of said electric valve means.

2. In combination, an alternating current circuit, a second circuit, electric translating apparatus connected therebetiveen and comprising an electric valve means having an anode and a cathode, means for controlling said translating apparatus to control the power factor at which power is transmitted to or received from said alternating current circuit, and a circuit for controlling said last mentioned means comprising means responsive to the negative anode-cathode voltage of said electric valve means.

3. In combination, an electric circuit, an electric valve means connected therein and having an anode, a cathode and a control member, an excitation circuit for energizing said control member to render said electric valve means conductive periodically including means for impressing a control voltage on said control member, and means for controlling said control voltage directly in response to the negative anodecathode voltage of said electric valve means.

l. In combination, an electric circuit, an electric valve connected therein. and comprising an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit for impressing on said control member a periodic voltage to render said electric valve means conductive periodically, and means responsive to the negative anode-cathode voltage for controlling said excitation circuit to control the phase of said periodic potential to maintain the commutating voltage of said electric valve means at a substantially constant value.

5. In combination, an electric circuit, an electric Valve means connected therein and comprising an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit for impressing on said control member a periodic voltage to render said electric valve means conductive periodically, and means comprising a unidirectional conducting device for introducing into said excitation circuit a voltage which varies in accordance with the negative anode-cathode voltage of said electric valve means to control the phase of said periodic voltage.

6. In combination, an electric circuit, an electric valve means connected therein and comprising an anode, a cathode and a control member, an excitation circuit for energizing said control member to render said electric valve means conductive periodically and comprising a saturable inductive device for impressin on said control member a periodic voltage of peaked wave form, said inductive device comprising a winding for controlling the phase of said periodic voltage, and means energized in accordance with the negative anode-cathode voltage of said electric valve means for controlling the energization of said control winding.

'7. In combination, an electric circuit, an electric valve means connected therein and comprising an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit for energizing said control member to render said electric valve means conductive periodically and including a saturable inductive device for impressing on said control member an alternating voltage of peaked wave form, said saturable inductive device comprising a control Winding for controlling the phase of said alternating voltage, and means comprising a unidirectional conducting device energized in accordance with the negative anode-cathode voltage of said electric valve means for energizing said control winding.

8. In combination, an electric circuit, an electric valve means connected therein and including an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit for energizing said control member to render said electric valve means conductive periodically and comprising means for impressing on said control member a periodic voltage, said means including a control winding for controlling the phase of said periodic voltage, and means for energizing said control winding comprising a unidirectional conducting device energized in accordance with the negative anodecathode voltage of said electric valve means and an energy storage circuit connected between said unidirectional conducing device and said control winding for impressing on said control Winding a unidirectional voltage.

9. In combination, an electric circuit, an electric valve means connected therein and including an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit fcr energizing said control member to render said electric valve means conductive periodically and comprising a saturable inductive device for impressing on said control member a periodic voltage, said inductive device including a control winding for controlling the phase of said periodic voltage, and means for energizing said control winding comprising a unidirectional conducting device energized in accordance with the negative anode-cathode voltage of said electric valve means and a reactive circuit connected between said unidirectional conducting device and said control winding for impressing on said control winding a unidirectional voltage.

10. In combination, an electric circuit, an electric valve means connected therein and comprising an anode, a cathode and a control member for controlling the conductivity thereof, an excitation circuit for energizing said control member to render said electric valve means conductive periodically and including a saturable inductive device having an exciting winding, a winding for impressing on said control member an alternating voltage of peaked wave form and a control winding for controlling the phase of said alternating voltage, a unidirectional conducting device energized in accordance with the negative anode-cathode voltage of said electric valve means, a reactive circuit including a capacitance connected to be charged through said unidirectional conducting device and being connected between said unidirectional conducting device and said control winding for impressing thereon a unidirectional voltage, and a voltage divider connected between said control winding and said reactive circuit for controlling the energization of said control winding.

11. In combination, an alternating current circuit, a direct current circuit, a plurality of electric valve means connected between said circults for transmitting power therebetween, said electric valve means each comprising an anode, a cathode and a control member, a plurality of excitation circuits for energizing said control members to render said electric valve means conductive periodically and in a predetermined order, and means energized in accordance with the negative anode-cathode voltages of said electric valve means for controlling said excitation circuits to control the power factor at which power is transmitted to or received from said alternating current circuit.

12. In combination, a polyphase alternating current circuit, a second circuit, a plurality of electric valve means connected between said circuits for transmitting power therebetween, each of said electric valve means comprising an anode, a cathode and a control member, a plurality of excitation circuits for energizing the control members to render said electric valve means conductive periodically and in a predetermined order, and a plurality of rectifying devices for producing electrical quantities responsive to the negative anode-cathode voltages of said electric valve means for controlling said excitation circuits.

13. In combination, a polyphase alternating current circuit, a second circuit, a plurality of electric valve means connected between said circuits and each comprising an anode, a cathode and a control member, a plurality of excitation circuits each associated with a different one of said electric valve means and comprising a saturable device for impressing on the associated control member a periodic voltage variable in phase, the saturable devices including control windings for controlling the phase of the periodic voltages, and a plurality of rectifying devices for supplying unidirectional current to said control windings in accordance with the negative anodecathode voltages of said electric valve means to control the power factor at which power is transmitted to or received from said alternating current circuit.

14. In combination, a polyphase alternating current circuit, a second circuit, electric valve translating apparatus connected between said circuits and including a plurality of pairs of serially connected electric valves, said electric valves each comprising an anode, a cathode and a control member, a plurality of excitation circuits each associated with a different one of said electric valve means for energizing the associated control member to render the electric valve means conductive periodically, said excitation circuits each including a saturable inductive device cornprising a winding for impressing on the associated control member an alternating voltage and a control winding for controlling the phase of said alternating voltage, and a plurality of rectifying devices responsive to the negative anodecathode voltage of the associated electric valves and a reactive circuit connected between the rectifying devices and the control windings for supplying unidirectional current to said control windings.

15.111 combination, a polyphase alternating current circuit, a second circuit, electric translating apparatus connected between said circuits comprising a plurality of electric valve means, each of said electric valve means including an anode, a cathode and a control member, a plurality of excitation circuits each associated with a different one of said electric valve means and each comprising means for impressing on the associated control member a periodic voltage variable in phase, and means for controlling said excitation circuits to control the power factor at which power is transmitted to or received from said alternating current circuit comprising a plurality of rectifying devices responsive to the anode-cathode voltages of said electric valve means for introducing into said excitation circuits electrical quantities for controlling the phase of the alternating voltages.

16. In combination, a polyphase alternating current circuit, a second circuit, electric translating apparatus connected between said circuits comprising a plru ality of electric valve means, each of said electric valve means including an anode, a cathode and a. control member, a plurality of excitation circuits each associated with a different one of said electric valve means and each including a saturable inductive device having a winding for impressing on the associated control member an alternating voltage of peaked wave form and a control winding for controlling the phase of the alternating voltage, and means for controlling said excitation circuits to control the power factor at which power is transmitted to or received from said alternating current circuit comprising a plurality of rectifying devices responsive to the negative anode-cathode voltages of said electric valve means and a filter circuit connected between said rectifying devices and the control winding to supply variable unidirectional current to said control winding.

17. In combination, a polyphase alternating current circuit, a second circuit, an electric translating apparatus connected between said circuits and including a plurality of electric valve means each having a control member, a plurality of excitation circuits for energizing the control members to render the electric valve means conductive in a predetermined order and during predetermined recurring intervals of time, and means for controlling each of the excitation circuits in accordance with the negative anode-cathode voltage of another of said electric valve means.

18. In combination, a polyphase alternating current circuit, a second circuit, an electric translating apparatus connected between said circuits and including a plurality of electric valve means each having an anode, a cathode and a control member, and a plurality of excitation circuits for energizing said control members to render the electric valve means conductive in a predetermined order, and means for controlling each of the excitation circuits in accordance with the negative anode-cathode voltage of another of said electric valve means comprising an energy storage circuit for producing an electrical quantity of predetermined phase position relative to the anode-cathode voltage of said another electric valve means.

19. In combination, a polyphase alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including an anode, a cathode and a control member, a plurality of excitation circuits each associated with a different one of said electric valve means for rendering said electric valve means conductive in a predetermined order and for predetermined recurring intervals, and means for controlling the excitation circuit of each of said electric valve means in accordance with the negative anode-cathode voltage of the electric valve means preceding it in the order of phase rotation.

20. In combination, a polyphase alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including an anode, a cathode and a control member, a plurality of excitation circuits each associated with a different one of said electric valve means for rendering said electric valve means conductive in a predetermined order and for predetermined recurring intervals, and means for control-ling the excitation circuit of each of said electric valve means in accordance with the negative anode-cathode voltage of the electric valve means succeeding it in the order of phase rotation.

21. In combination, an alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including a control member for controlling the conductivity thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for impressing a periodic voltage on the control member of the assocciated electric valve means, and means responsive to the currents conducted by the electric valve means for controlling said excitation circuits to control the power factor at which power is transmitted to or received from said alternating current circuit.

22. In combination, an alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including a control member for controlling the conductivity thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for impressing a periodic voltage on the control member of the associated electric valve means, and means comprising a plurality of inductive devices and rectifying devices for controlling the phase of the periodic voltages in accordance with the currents conducted by said electric valve means to control the power factor at which power is transmitted to or received from said alternating current circuit.

23. In combination, an alternating current circuit, a second circuit, electric translating apparatus connect-ed between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including a control member for controlling the conductivity thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for impressing a periodic voltage on the control member of the associated electric valve means to cause said electric valve means to conduct current during predetermined intervals, and means comprising inductive reactances responsive to the currents conducted by said eleotric valve means for controlling the phase of periodic voltage in accordance with the final rat v of the change of the commutating voltage of electric valve means.

24. In combination, an alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for trans-- mitting power therebetween and comprising a plurality of electric valve means each includ ng a control member for controlling the conductivitv thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for impressing a periodic voltage on the control member of the associated electric valve means, and means comprising linear inductive reactances responsive to the currents conducted by said electric valve means to control the phase of the periodic voltages in accordance with the maximum commutating voltages of said electric valve means.

. In combination, an alternating current circuit, a direct current circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including a control member for controlling the conductivity thereof, a plurality of excitation circuits each associated with a different one of said electric valve means for impressing a periodic voltage on the control member of the associated electric valve means, and means comprising nonlinear inductive reactances responsive to the current. conducted by said electric valve means to control the phase of the periodic voltages relative to the voltage of said alternating current circuit in accordance with the minimum rate of change of the commutating voltages of said electric valve means.

In combination, an alternating current circuit, a second circuit, electric translating apparatus connected between said circuits for transmitting power therebetween and comprising a plurality of electric valve means each including a control member for controlling the conductivity thereof, a plurality of excitation circuits each ssociated with a different one of said electric valve means for impressing a periodic voltage on the control member of the associated electric valve means, a plurality of inductive devices each connected in series relation with a different electrio valve means and each comprising means for producing a voltage which varies in accordance with the commutating voltage of the associated electric valve means, and rectifying means energized from said last mentioned means for supplyvariable unidirectional currents to said excitation circuits in accordance with the voltages produced by said inductive devices.

27. In combination, an alternating current circuit, a second circuit, electric translating appaconnected between said circuits and comprising an electric valve means having an anode and a cathode, inductive means associated with said translating apparatus for controlling the power factor at which power is transmitted to received from said alternating current circuit, ann a circuit for controlling said inductive means comprising means responsive to the negative anode-cathode voltage of said electric valve means.

In combination, an alternating current circuit, a second circuit, electric translating apparatus connected between said circuits and comprising an electric valve means having an anode and a cathode, a variable impedance inductive means connected across said alternating current circuit for controlling the power factor at which power is transmitted to or received from said alternating current circuit, and means for cong the impedance of said variable impedance inductive means in accordance with the negative anode-cathode voltage of said electric valve means.

29. In combination, an alternating current cireut. a second circuit, electric translating apparatus connected between said circuits and comprising an electric valve means having an anode and a cathode, inductive means associated with said translating apparatus for controlling the power factor at which power is transmitted to or received from said alternating current circuit, said inductive means comprising a control winding for controlling the amount of reactive voltamperes transmitted to or received from said alternating current circuit, and a circuit for energizing said control winding comprising means energized in accordance with the negative anodecathode voltage of said electric valve means and rectifying means for supplying to said control winding unidirectional current which varies in accordance with the commutating voltage of said electric valve means.

BURNICE D. BEDFORD. 

